This invention relates to fluid pumping devices and more particularly to fluid pumping devices that emit small quantities of fluid having a volume in the order of picoliters.
Fluid pumping devices have a wide variety of applications and are designed according to the specific application. In medical diagnostic applications, for example, fluid pumping devices are incorporated into diagnostic systems that require these devices to supply small, accurate, quantities of fluid. Medical diagnostic applications include, for example, combustion and mass spectrometric analysis systems, microfraction collector devices, and digital ultramico pipette devices.
In combustion and mass spectrometric analysis systems, for example, a fluid pumping device continually sweeps an electrophoresis column and ejects the effluent into a pyrolyzer oven. The accuracy of the analysis is dependent, on the pumping device providing accurate, highly repeatable, small quantities of fluid. That is to say, as the volume of the fluid decreases, the concentration of ions injected into the pyrolyzer oven increases, and accordingly facilitates an increase in accuracy of the analysis. As is known by those skilled in the art, systems employing electrophoresis techniques are valuable diagnostic tools in the quantitative study of individual molecules in a complex natural mixture such as blood and other body fluids DNA, RNA, and polypeptides are often separated by electrophoresis.
Conventional fluid pumping devices lack the ability of providing highly accurate, highly repeatable small quantities of fluid; fluid quantities having a volume in the order of picoliters. Conventional fluid pumping device designs do not lend themselves to supply accurate highly repeatable small quantities of fluid required in highly accurate analyzing systems. Consequently, there exists a need for fluid pumping devices that can selectively eject a fluid having a volume in the order of picoliters.